Informational masking in normal-hearing and hearing-impaired listeners

The present study aimed to test whether central, across-channel, informatio nal auditory processing abilities are altered by hearing loss. The informat ional masking effect exerted on a 1 kHz tone-pip by a simultaneous four-ton e masker, whose spectral content changed within as well as across trials, w as measured in the left and right ears of normal-hearing subjects and heari ng-impaired subjects with either symmetrical or asymmetrical hearing loss b etween the two ears. In the subjects with normal-hearing or symmetrical hea ring loss, the level of the masker was set to 40 dB SL in each ear, in the subjects with asymmetrical hearing loss, the masker was set to 40 dB SL in the best ear and loudness-balanced in the other ear. The results failed to reveal significant differences in informational masking between normal-hear ing and hearing-impaired subjects. However, in subjects with asymmetric hea ring loss, less informational masking was observed in the ear with the more elevated absolute thresholds than in the opposite ear. Since the latter fi nding can be explained in terms of across-ear differences in loudness recru itment, it is suggested that central, across-channel, informational process ing abilities are not substantially different in hearing-impaired than in n ormal-hearing ears.